Electromagnetic safety device having a non-rotatable armature



United States Patent 3,259,811 ELECTROMAGNETIC SAFETY DEVICE HAVING A NON-ROTATABLE ARMATURE William R. Dunn, Los Angeles, Calif, assignor to Honeywell Inc., a corporation of Delaware Filed Aug. 17, 1964, Ser. No. 389,995 5 Claims. (Cl. 317-191) This invention relates to gas safety controls and, more specifically, to a thermocouple energizable power unit for use in such a control. The control may be in the form of a valve or a switch adapted to control a valve, in a gas heating system.

Controls of the above-mentioned type are well known in the art, which, incidentally, is highly developed. It is the constant aim of the gas controls manufacturers to make controls more reliable and less expensive. This invention is directed specifically to an improved power unit for operating a safety control, with the unit being of less expensive construction. Most of the cost reduction of the power unit of this invention, over the prior art, lies in the structure which enables the unit to require less testing thereof.

One of the objects of the invention is to provide a thermocouple energizable power unit that is of reliable and inexpensive construction.

Another object of the invention is to provide an electric power unit which will not change in its operating characteristics over a long period of time.

Other objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying drawing wherein:

FIGURE 1 is a side view of a safety valve broken away to show a vertical section View of the power' unit as applied to this valve; and,

FIGURE 2 is a fragmentary view, taken along line 22 of FIGURE 1, showing a portion of the unit in cross section.

The valve body, generally designated by the reference numeral 11, is the same as the valve body illustrated in Patent No. 2,746,472, granted to M. G. Sogge on May 22, 1956. Included in the valve body is a manually rotatable plug valve (not shown) that is rotatable between off, pilot and on positions by an actuating stem 12 that is axially slidable in the plug valve through a pin and slot connection therewith. The stem is adapted to be actuated by a control knob 13 and'is axially movable against the bias of a coil spring 14 to bring an annular abutment member 15 into engagement with an arm 16 of a lever 17. The lever 17 is pivoted in the valve body on a pivot 18, at one end of the lever, while the other end of the lever carries a safety valve 19.

As the details of the safety valve and the actuating mechanism between the plug valve, control knob and safety valve form no part of this invention but is merely an illustration of one type of control apparatus that is adapted to be controlled by the invention to b presently described, it will suffice to state that the operation thereof is the same as the valve in the above-mentioned Sogge patent. Obviously, instead of the valve 19, for directly controlling the flow of gas through the valve body in which the valve is mounted, a switch could be used in place of the valve to indirectly control an electrically operated gas valve located at some other part of a gas heating installation.

The .power unit of this invention is generally designated by the reference numeral 20 and consists of a cup-shaped housing 21 having an open end 22 and an apertured closed end 23. The open end of the housing is closed by an electromagnet sub-assembly including a sleeve 24 with an inwardly extending annular flange 26 at one end thereof.

3,259,811 Patented July 5, 1966 A U-shaped electromagnet core member 27 is mounted on a reduced diameter portion of an insulator 28 which, in turn, fits tightly in the sleeve 24, with a second reduced diameter portion thereof extending through the opening formed by the flange 26. An electric terminal member 29 extends through an insulating washer 30 and through the center of the insulator 28 and through an insulating washer 31 and is headed over the washer 31 to retain the electromagnet core 27 on the insulator 28. The housing 21 is rolled over the peripheral edge of a flange 25 at the other end of the sleeve 24 to rigidly secure the flange 25 in the open end of the housing. Two coils of wire 32 and 33, which are electrically connected in series, has one end thereof (not shown) soldered to the head portion 29b, with the other end thereof (not shown) soldered to the flange 25.

An armature 34, in the form of a disc, has an aperture 35 therein through which an armature stem 36 (preferably non-round in cross-section) extends. beveled at the surface of the armature facing the magnet and is engaged by a rounded head 36a on the adjacent end of the stem 36. A spiral compression spring 37 has the smaller diameter end thereof bearing against the armature at a substantial distance from the armature stem, while the larger diameter end of the spring bears against the inner surface of the housing end 23 near the side wall thereof. The function of this spring is to prevent rotation of the armature with respect to the end 23 and therefore with respect to the magnet core 27, which is fixed with respect to the housing 21. The stem 36 extends through a round hole in the closed end of the housing or, preferably, through a hexagonal bore in a bearing sleeve 38, which has a hexagonal extension 38a that snugly fits in a hexagonal opening in the wall 23. An annular rib 38b bears against the outer surface of the wall 23 and is normally held against the wall 23 by means of a coil spring 39. The spring 39 bears against an adjustable washer-shaped spring retainer 40 screw-threaded onto threads formed on the exterior surface of the bearing sleeve 38. The other end of th spring 39 bears against a similar shaped spring retainer 41 which, in turn, bears against the lever 17 carrying the valve 19. The armature stem 36 is operably connected to the lever 17 by having a reduced diameter portion 36b thereof extending through an aperture in the lever 17 and through a bearing nut 42 secured to the end of the extension 36b in any conventional manner, as in the Sogge patent. A clip-type washer 43 frictionally engages sleeve 24 to secure the power unit in place.

The electromagnet unit 20 is adapted to be connected to a conventional thermocouple (not shown) by having a suitable lead clip connected to the terminal member 29 with another lead clip either connected to the sleeve 24 or to a pipe connected to the valve body 11. The spring 39 is much stronger than the spring 37 so that the armature is normally held away from the magnet core -27 but is adapted to be compressed by the knob 13 being moved axially, to engage the arm 16 on the lever 17, and to pivot the lever 17 clockwise about the pivot 18 to move the armature stem sufficiently far to place the armature 34 in engagement with the core 27, the spring 37 causing the armature 34 to slow the movement on stem 36. Due to the fact that there are substantially no forces tending to rotate the armature 34 on the stem 36 and due to the fact that the friction between the spring 37 and the armature is greater than the friction between the armature and the head 36a or that the stem 36 is nonrotatable in the wall 23, there will never be any change in the angular position of the armature 34 with respect to the ends of the core 27. By always having the same portions of armature 34 engage the core 27, extensive testing of the drop out characteristics of the assembly The aperture 35 is is reduced. Except for providing for this consistent positioning of the armature with respect to the core, it would be necessary to provide a plurality of tests at various angular positions of the armature with respect to the core 27, to be assured that the armature would be forced away from the core 27 when the energization of the magnet drops to a predetermined, fairly critical amount. By the elimination of a great amount of the testing of the units, the cost of the manufacture thereof is considerably reduced. While other means could be provided to assure no change in the angular position of the armature with respect to the magnet core, most prior art methods of accomplishing this function have been in the nature of more expensive constructions with additional dangers of faulty operation. Therefore, the scope of the invention should be determined from the appended claims.

Iclaim:

1. An electric power unit, adapted to be energized by a thermocouple heated by a pilot burner for control-ling a safety device, comprising a housing, an electromagnet mounted on a wall of said housing, an armature positioned in said housing and movable into and out of engagement with said electromagnet, an actuator for said armature, a swivelled connection between said actuator and said armature, and resilient means positioned in said housing and engaging said armature so as to prevent rotation of the armature about the axis thereof which is perpendicular to the electromagnet engaging surface thereof.

2. An electric power unit, adapted to be energized by a thermocouple heated by a pilot burner for controlling a safety device, comprising a housing, an electromagnet mounted on a Wall of said housing, an armature positioned in said housing and movable into and out of engagement with said electromagnet, an actuator for said armature, means for biasing said armature away from said electromagnet, a swivelled connection between said actuator and said armature, and resilient means positioned in said housing and engaging said armature so as to prevent rotation of the armature about the axis thereof surface thereof.

3. A control device comprising a housing, an electromagnet mounted on a wall of said housing, an armature positioned in said housing and movable into and out of engagement with said electromagnet, an actuator for said armature, a swivelled connection between said actuator and said armature, control means operably connected to said actuator, and resilient means positioned in said housing and engaging said armature so as to prevent rotation of the armature about the axis thereof which is perpendicular to the electromagnet engaging surface thereof.

4. A low voltage electric power unit for operating a control device and comprising a housing, an electromagnet rigidly mounted in one end of said housing, an armature stem axially slidable through an apertured other end of said housing, an armature swivelly mounted on one end of said stem and within said housing, the other end of said stem being adapted to perform an operating function, means normally biasing said armature away from said electromagnet but yieldable to permit said armature to be placed into engagement with said electro magnet, and resilient means in said housing and bearing against said armature so as to prevent said armature from rotating about the axis of said armature stem.

5. A low voltage electric power unit for operating a control device and comprising a housing, an electromagn-et rigidly mounted in one end of said housing, an armature stem axially slidable through an apertured other end of said housing, said armature stem being nonrotatable in said apertured other end, an armature swivelly mounted on one end of said stem and within said housing, the other end of said stem being adapted to perform an operating function, means normally biasing said armature away from said electromagnet but yieldable to permit said armature to be placed into engagement with said electromagnet, and resilient means in said housing and bearing against said armature so as to prevent said armature from rotating about the axis of said armature stem.

No references cited.

BERNARD A. G'ILLHEANY, Primary Examiner.

G. HARRIS, JR., Assistant Examiner. 

1. AN ELECTRIC POWER UNIT, ADAPTED TO BE ENERGIZED BY A THERMOCOUPLE HEATED BY A PILOT BURNER FOR CONTROLLING A SAFETY DEVICE, COMPRISING A HOUSING, AN ELECTROMAGNET MOUNTED ON A WALL OF SAID HOUSING, AN ARMATURE POSITIONED IN SAID HOUSING AND MOVABLE INTO AND OUT OF ENGAGEMENT WITH SAID ELECTROMAGNET, AN ACTUATOR FOR SAID ARMATURE, A SWIVELLED CONNECTION BETWEEN SAID ACTUATOR AND SAID ARMATURE, AND RESILIENT MEANS POSITIONED IN SAID HOUSING AND ENGAGING SAID ARMATURE SO AS TO PREVENT ROTATION OF THE ARMATURE ABOUT THE AXIS THEREOF WHICH IS PERPENDICULAR TO THE ELECTROMAGNET ENGAGING SURFACE THEREOF. 